Pāhoehoe lava overflows from this open lava channel on the island of Hawaiʻi as a result of a fissure vent eruption. The channel is crusting over with a V-shaped opening pointing upstream. The crusting-over process usually starts at the upstream end. The crust grows downstream for a considerable distance, then the crust founders and sinks, opening the channel to crusting over again.Photo credit: Mila Zinkova